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Porphyrias

by Kevin Ahern, PhD
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    00:02 Now, porphyrias are diseases that I've described as we went through this relating to the deficiencies of enzymes in the synthesis of heme.

    00:12 They're unusual and they actually have some interesting historical significance.

    00:16 They arise from deficiencies as I said and the accumulation of the porphyrins that arise by the deficiencies of those enzymes.

    00:24 Acute porphyrias can cause brain and nerve problems and can be fatal.

    00:29 More commonly, however, other porphyrias involve things like severe abdominal pain, vomiting, neuropathy and mental issues.

    00:37 And those mental issues can be unpredictable.

    00:39 A person could be perfectly normal and then all of a sudden act in an insane fashion.

    00:44 And that relates to some historical significance I'll talk about.

    00:48 The porphyrias can also arise from heavy metal poisoning.

    00:51 One of the enzymes of the process you recall was very sensitive to heavy metals like lead.

    00:57 This can also arise from drugs that affect some liver enzymes that are important for making these heme molecules.

    01:04 Now, defects of any heme synthesis enzyme can give rise to a type of porphyria.

    01:10 Liver disease can also cause porphyria.

    01:13 Now, porphyrias can be manifested and seen in skin problems that arise when they accumulate in the skin and fluoresce as seen in this photo.

    01:22 Teeth may be deformed in some porphyrias and discolored as shown here.

    01:26 Gum and eye abnormalities are also known.

    01:29 The skin can be discolored and you can see some discoloration here.

    01:33 And some of that discoloration can go away on exposure to light because these compounds are sensitive to light.

    01:39 And the people who have them themselves are sensitive to light.

    01:43 They will avoid light.

    01:45 Now, the historical significance; the madness of King George, the person who is king at the time the American colonies revolted, was said to have intermittent mental issues.

    01:57 And it was believed that King George suffered from porphyria and the madness of King George was due to a genetic disease.

    02:04 It is known for example that his ancestor did have the disease.

    02:08 Now a more interesting significance with respect to history, actually relates to something that manifests itself in the types of symptoms that some people with porphria exhibit.

    02:19 Remember that some people have discolored skin and some people are very sensitive to light.

    02:25 And it is thought that the porphyria may have been associated with the vampire legends.

    02:30 The thought of the vampire legends was that the people were actually deficient in hemoglobin and what they were trying to do is get blood.

    02:37 Well, in fact, it was actually the opposite that was happening.

    02:40 But that doesn't really matter.

    02:41 What matters is that we have the vampire legend that may have arisen as a result of people's misunderstanding of what happened in porphyria.


    About the Lecture

    The lecture Porphyrias by Kevin Ahern, PhD is from the course Amino Acid Metabolism.


    Included Quiz Questions

    1. ...an accumulation of porphyrins.
    2. ...an accumulation of heme.
    3. ...defects in any heme breakdown enzyme.
    4. All of the answers are correct.
    5. None of the answers are correct.

    Author of lecture Porphyrias

     Kevin Ahern, PhD

    Kevin Ahern, PhD


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